From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH] netfilter: fix nf_conntrack_l4proto_register() Date: Fri, 29 Oct 2010 19:57:02 +0200 Message-ID: <1288375022.2560.306.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , netdev , Netfilter Development Mailinglist To: Patrick McHardy Return-path: Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org While doing __rcu annotations work on net/netfilter I found following bug. On some arches, it is possible we publish a table while its content is not yet committed to memory, and lockless reader can dereference wild pointer. Signed-off-by: Eric Dumazet --- net/netfilter/nf_conntrack_proto.c | 6 ++++++ 1 files changed, 6 insertions(+) diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c index ed6d929..dc7bb74 100644 --- a/net/netfilter/nf_conntrack_proto.c +++ b/net/netfilter/nf_conntrack_proto.c @@ -292,6 +292,12 @@ int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto) for (i = 0; i < MAX_NF_CT_PROTO; i++) proto_array[i] = &nf_conntrack_l4proto_generic; + + /* Before making proto_array visible to lockless readers, + * we must make sure its content is committed to memory. + */ + smp_wmb(); + nf_ct_protos[l4proto->l3proto] = proto_array; } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != &nf_conntrack_l4proto_generic) {